The Astrophysical Journal Supplement Series, 164:52–80, 2006 May # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A.

MULTIWAVELENGTH FORMATION INDICATORS: OBSERVATIONS1,2 H. R. Schmitt,3,4,5,6 D. Calzetti,7 L. Armus,8 M. Giavalisco,7 T. M. Heckman,7,9 R. C. Kennicutt, Jr.,10,11 C. Leitherer,7 and G. R. Meurer9 Received 2005 May 31; accepted 2005 November 13

ABSTRACT We present a compilation of multiwavelength data on different indicators for a sample of nearby star forming . Here we discuss the observations, reductions and measurements of ultraviolet images obtained with STIS on board the (HST ), ground-based H, and VLA 8.46 GHz radio images. These observations are complemented with infrared fluxes, as well as large-aperture optical, radio, and ultraviolet data from the literature. This database will be used in a forthcoming paper to compare star formation rates at different wave bands. We also present spectral energy distributions (SEDs) for those galaxies with at least one far-infrared mea- surements from ISO, longward of 100 m. These SEDs are divided in two groups, those that are dominated by the far-infrared emission, and those for which the contribution from the far-infrared and optical emission is comparable. These SEDs are useful tools to study the properties of high- galaxies. Subject headinggs: galaxies: evolution — galaxies: starburst — infrared: galaxies — radio continuum: galaxies — : formation — ultraviolet: galaxies

1. INTRODUCTION In recent years, all wavelength regions have been exploited to track down star formation at all and trace the star forma- The global star formation history of the universe is one of the crucial ingredients for understanding the evolution of galaxies tion history of the universe. At high redshift the Lyman-break gal- axies (Steidel et al. 1996, 1999) provide the bulk of the UV light as a whole, and for discriminating among different formation from star formation, while SCUBA has been used to detect the scenarios (Madau et al. 1998; Ortolani et al. 1995; Baugh et al. brightest FIR sources in the range 1 P z P 3 4(e.g.,Bargeretal. 1998). Star formation is traced by a number of observables, often 1999, 2000; Smail et al. 2000; Chapman et al. 2003). The Lyman- complementary to each other. The ultraviolet (UV) is where the breakgalaxiesare,byselection,activelystar-formingsystems, bulk of the energy from young, massive stars is emitted, but it resembling local starburst galaxies in many respects (Pettini et al. suffers from the effects of dust extinction. The nebular emission 1998; Meurer et al. 1997, 1999), and possibly covering a large line H is a tracer of ionizing photons, and thus of young, mas- range in metal and dust content (Pettini et al. 1999; Steidel et al. sive stars, but it is also affected by assumptions about the stellar 1999; Calzetti 1997). The SCUBA sources occupy the high end of initial mass function. The far-infrared (FIR) emission comes from the dust-processed stellar light and reliably tracks star formation in the FIR luminosity function of galaxies (Blain et al. 1999), and are dust-rich objects. The relationship between the UV-selected and moderately to very dusty galaxies, but it is not a narrowband mea- FIR-selected luminous systems is not yet clear. Whether the two surement (like the UVor H) and needs to be measured across the typesofgalaxiesrepresenttwodistinctpopulationsorthetwo entire infrared wavelength range. Finally, the nonthermal radio ends of the same population is still subject to debate (Adelberger emission is a tracer of the activity in galaxies, but suf- & Steidel 2000). The answer to this question can drastically change fers from uncertain calibration. our understanding of the evolution, star formation history, and metal/dust enrichment of galaxies. 1 Based on observations made with the NASA/ESA Hubble Space Telescope, The difficulty in relating the two types of galaxies stems from which is operated by the Association of Universities for Research in Astronomy, the paucity of simultaneous UV, H, FIR(>100 m), and radio Inc., under NASA contract NAS5-26555. 2 data for both low- and high-z galaxies. While multiwavelength Based on observations obtained with the Apache Point Observatory 3.5 m observations of high-z galaxies are hampered at present by the telescope, which is owned and operated by the Astrophysical Research Consortium. 3 Remote Sensing Division, Code 7210, Naval Research Laboratory, 4555 sensitivity and positional accuracy limitations of current instru- Overlook Avenue, Washington, DC 20375; [email protected]. mentation, multiwavelength observations of local galaxies are 4 Interferometrics, Inc., 13454 Sunrise Valley Drive, Suite 240, Herndon, VA20171. possible and are key for producing the spectral energy distribu- 5 Visiting Astronomer, Cerro Tololo Inter-American Observatory, National tions (SEDs) that can be used as templates for higher redshift Optical Astronomy Observatories, which are operated by AURA, Inc., under a cooperative agreement with the National Science Foundation. observations. To be representative, such SEDs should cover as 6 Visiting Astronomer Kitt Peak National Observatory, National Optical As- completely as possible the parameter range of properties (metal- tronomy Observatories, which are operated by AURA, Inc., under a cooperative licity, luminosity, etc.) of galaxies. agreement with the National Science Foundation. 7 This paper presents a large, homogeneous data set of multi- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD wavelength observations of 41 local (closer than 120 Mpc) star- 21218. 8 Spitzer Science Center, California Institute of Technology, Mail Stop 220-6, forming galaxies, spanning from the UV to the radio. The UV Pasadena, CA 91125. observations are from our own HST STIS imaging centered at 9 Department of Physics and Astronomy, The Johns Hopkins University, 1600 8. The optical (H) and radio (6 cm and 21 cm) data are Baltimore, MD 21218. from ground-based programs complementary to the HST obser- 10 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721. vations. The FIR data are from archival Infrared Astronomical 11 Institute of Astronomy, University of Cambridge, Madingley Road, Satellite (IRAS) and Infrared Space Observatory (ISO) observa- Cambridge, CB3 0HA, UK. tions spanning the wavelength range 12–200 m. 52 MULTIWAVELENGTH STAR FORMATION INDICATORS 53

TABLE 1 Sample Characteristics

Velocity Distribution a ; b Name (J2000.0) (J2000.0) (km s1) (Mpc) (arcmin) E(BV ) Morphology (1) (2) (3) (4) (5) (6) (7) (8)

ESO 350-38 ...... 0 36 52.5 33 33 19 6132 81.8 0.5 ; 0.3 0.01 Merger NGC 232...... 0 42 45.8 23 33 41 6682 89.1 1.0 ; 0.8 0.01 SB(r)a pec Mrk 555 ...... 0 46 05.6 01 43 25 4156 55.4 1.4 ; 1.2 0.02 SA(rs)b pec IC 1586 ...... 0 47 56.1 22 22 21 5963 79.5 0.3 ; 0.3 0.02 BCG NGC 337...... 0 59 50.3 07 34 44 1702 20.7 2.9 ; 1.8 0.08 SB(s)d IC 1623 ...... 1 07 47.2 17 30 25 6016 80.2 0.7 ; 0.4 0.01 Merger NGC 1155...... 2 58 13.0 10 21 04 4549 60.7 0.8 ; 0.7 0.04 Compact UGC 2982...... 4 12 22.6 05 32 51 5273 70.3 0.9 ; 0.4 0.14 Sm NGC 1569...... 4 30 49.3 64 50 54 40 1.6 3.6 ; 1.8 0.51 IBm NGC 1614...... 4 34 00.0 08 34 45 4681 62.4 1.3 ; 1.1 0.06 SB(s)c pec NGC 1667...... 4 48 37.1 06 19 13 4459 59.5 1.8 ; 1.4 0.06 SAB(r)c NGC 1672...... 4 45 42.1 59 14 57 1155 14.5 6.6 ; 5.5 0.00 SB(r)bc NGC 1741...... 5 01 37.9 04 15 35 3956 52.8 1.5 ; 1.0 0.06 Merger NGC 3079...... 10 01 57.8 55 40 49 1182 20.4 7.9 ; 1.4 0.00 SB(s)c NGC 3690...... 11 28 32.6 58 33 47 3121 41.6 3.0 ; 3.0 0.00 Merger NGC 4088...... 12 05 35.6 50 32 32 825 17.0 5.8 ; 2.2 0.00 SAB(rs)bc NGC 4100...... 12 06 08.7 49 34 56 1138 17.0 5.4 ; 1.8 0.01 (R’)SA(rs)bc NGC 4214...... 12 15 40.0 36 19 27 313 3.5 8.5 ; 6.6 0.00 IAB(s)m NGC 4861...... 12 59 00.3 34 50 48 880 17.8 4.0 ; 1.5 0.01 SB(s)m: NGC 5054...... 13 16 58.4 16 38 03 1630 27.3 5.1 ; 3.0 0.03 SA(s)bc NGC 5161...... 13 29 14.4 33 10 29 2247 33.5 5.6 ; 2.2 0.04 SA(s)c: NGC 5383...... 13 57 05.0 41 50 44 2333 37.8 3.2 ; 2.7 0.00 (R’)SB(rs)b:pec Mrk 799 ...... 14 00 45.8 59 19 44 3157 42.1 2.2 ; 1.1 0.00 SB(s)b NGC 5669...... 14 32 44.1 09 53 24 1387 24.9 4.0 ; 2.8 0.01 SAB(rs)cd NGC 5676...... 14 32 46.8 49 27 30 2237 34.5 4.0 ; 1.9 0.01 SA(rs)bc NGC 5713...... 14 40 11.3 00 17 26 1872 30.4 2.8 ; 2.5 0.03 SAB(rs)bc pec NGC 5860...... 15 06 33.4 42 38 29 5520 73.6 1.0 ; 1.0 0.01 Peculiar NGC 6090...... 16 11 40.8 52 27 27 8953 119.4 1.0 ; 1.0 0.00 Peculiar NGC 6217...... 16 32 39.3 78 11 53 1544 23.9 3.0 ; 2.5 0.04 (R)SB(rs)bc NGC 6643...... 18 19 46.0 74 34 09 1686 25.5 3.8 ; 1.9 0.06 SA(rs)c UGC 11284...... 18 33 35.5 59 53 20 8650 115.3 2.0 ; 2.0 0.05 Merger NGC 6753...... 19 11 23.4 57 02 56 3073 41.0 2.5 ; 2.1 0.06 (R’)SA(r)b Tol 1924416...... 19 27 58.0 41 34 28 2863 38.2 0.8 ; 0.4 0.08 Peculiar NGC 6810...... 19 43 34.2 58 39 21 1888 25.3 3.2 ; 0.9 0.04 SA(s)ab:sp ESO 400-43 ...... 20 37 41.8 35 29 04 6032 80.4 0.5 ; 0.4 0.02 Compact NGC 7496...... 23 09 47.0 43 25 40 1623 20.1 3.3 ; 3.0 0.01 (R’)SB(rs)bc NGC 7552...... 23 16 11.0 42 34 59 1568 19.5 3.4 ; 2.7 0.01 (R’)SB(s)ab Mrk 323 ...... 23 20 22.7 27 18 56 4404 58.7 1.0 ; 0.7 0.05 SBc NGC 7673...... 23 27 41.3 23 35 23 3581 47.8 1.3 ; 1.2 0.04 (R’)SAc pec. NGC 7714...... 23 36 14.1 02 09 18 2925 39.0 1.9 ; 1.4 0.04 SB(s)b:pec Mrk 332 ...... 23 59 25.6 20 45 00 2568 34.2 1.4 ; 1.3 0.04 SBc

Notes.—Col. (1): name. Cols. (2) and (3): Right ascension and declination, respectively, in J2000.0 coordinates. Col. (4): Radial velocities relative to 1 1 the Local Group. Col. (5): Distances obtained from Tully (1988) for the nearest galaxies, or calculated from the radial velocities assuming H0 ¼ 75 km s Mpc . Col. (6): Galaxies’ major and minor axis diameters (D 25). Col. (7): Galactic foreground reddening, obtained preferentially from Burstein & Heiles (1982), or from Schlegel et al. (1998) when the former was not available. Col. (8): Morphological types.

The data in this paper provide a uniform data set, in terms of icant variation between the final fluxes. The sample is composed type of data, reduction, and calibration strategies in each wave- of 41 galaxies, which were selected according to the following cri- length range, that will be used in an accompanying paper to reeval- teria: (1) IRAS 100 mfluxk1 Jy, to ensure detection with the ISO uate star formation rate indicators at the different wavelengths. long-wavelength camera; (2) recession velocity 9000 km s1,to resolve spatial scales as small as 35 pc with STIS, which is the 2. SAMPLE scale of large OB associations or giant molecular clouds; (3) mean 0 The global list of galaxies in our sample is presented in Table 1, angular diameter D25 P 4 , to ensure that the sources were seen where we give their coordinates, radial velocities, distances, diam- as pointlike by the ISO long-wavelength camera; (4) L(H) > eters, morphological types, and foreground Galactic reddening. 1039 ergs s1 in the central 500 –1000,toselectactive,centrallystar- We gave preference to Galactic reddening values from Burstein & forming objects; (5) no, or at worst weak, nonthermal nuclear ac- Heiles (1982) instead of Schlegel et al. (1998), because for gal- tivity, as determined by the nuclear emission line properties of the axies with high foreground reddening, such as NGC 1569, the lat- galaxies (e.g., Ho et al. 1997). We retained only four of these ac- ter values result in too high a correction (i.e., an unphysically blue tive galaxies in our sample, those for which the nuclear spectrum spectrum). Nevertheless, this correction is usually very small, and (inner 200) shows emission-line ratios typical of active galactic the difference between the two values does not introduce a signif- nuclei (AGNs), while a more extended spectrum, encompassing a 54 SCHMITT ET AL. Vol. 164 region of 1000 or larger, has emission-line ratios typical of H ii re- tions of Mrk 555, which resulted in the drifting of the spacecraft. gions. Based on the comparison of the nuclear and integrated H This produced slightly elongated point sources, but did not affect or radio emission, we estimate that the AGN contributes to, at most, the integrated flux of this galaxy. 10% of the total luminosity in these galaxies. The reduction and calibration of the data followed standard Our sample specifically excluded ultraluminous infrared gal- procedures. The images of the galaxies in our snapshot project axies (ULIRGs), because data for a significant number of such were obtained in single exposures of 1320 s each. Only IC 1623 sources are available from the literature (Goldader et al. 2002), had its observations split into multiple exposures, which had to obtained in a instrumental configuration similar to ours. Our pro- be registered and combined. Background levels and standard ject aimed to cover the IR luminosity range of more normal gal- deviations () were determined on emission-free regions of the axies, thus extending the low bound of this parameter by a factor images. The images were background-subtracted, clipped at the 103, in order to accommodate the fact that high-redshift galax- 3 level (pixels with flux lower than 3 were set to zero) and ies may not all be as IR-luminous as ULIRGs. Nevertheless, we flux calibrated using the information available in their headers. collected the data available on ULIRGs in the literature and will The UV fluxes of the galaxies, obtained by integrating the emis- take them into consideration in our analysis paper (Schmitt et al. sion in the final images, as well as the 3 detection limits, are 2006). given in Table 3. These values are not corrected for Galactic The final sample covers a wide range of intrinsic properties. extinction. The host galaxy morphologies vary from regular spiral galaxies to Throughout this paper we use the technique of measuring the interacting/merging systems. The bolometric luminosities, cal- fluxes of the images inside the 3 level, not by integrating every- culated based on the infrared luminosities and the correction fac- thing inside a given aperture. The reason for making a cut at the tor given by Calzetti et al. (2000), vary by a factor of almost 1000, 3 level is to avoid spurious background variations and flat- 8 with NGC 1569 having Lbol 7 ; 10 L, while IC 1623 has fielding errors. We test the effect of this technique on the fainter, 11 4:7 ; 10 L, close to the ULIRG limit. This sample also covers lower surface brightness sources by comparing measurements a large factor in star formation activity, from the poststarburst in of both H and UV done in this way with measurements done NGC 1569 up to the FIR-luminous starburst in IC 1623; as well as without clipping the images at the 3 level. We find that in most afactorof10 in metallicity, from metal-poor galaxies such as cases the difference between the two techniques is negligible, Tol 1924416, which has ½O/H¼8:0, to metal-rich ones such while in the worst cases it can represent a 5% difference in the as NGC 7552, which has ½O/H¼9:3 (Storchi-Bergmann et al. total H flux, well within our measurement uncertainties (see 1994). Although this sample covers a wide range of intrinsic prop- below). Another way to estimate that this approach will cause an erties, one should keep in mind that it was culled from the ISO insignificant error to the integrated fluxes is based on the fact that archive, so the galaxies may have been observed because of some the area covered by pixels between 3 and 6 is small, as can be characteristic of particular interest for the original observers. As a seen in the figures, suggesting that the area associated with the result, the final sample may not necessarily be representative of object and covered by pixels below 3 should also be small. typical galaxies. Combining this information with the fact that the 3 flux level Complete UV-H-radio coverage is achieved for 26 out of is very small compared to the regions where the bulk of the 41 galaxies, due to various limitations (e.g., snapshot nature of the emission originates, indicates that this approach will not change HST observations, weather, declination of the source). Complete the measured flux significantly. The errors involved in the UV flux coverage using our own data was obtained for 13 galaxies, with measurements are of the order of 5%. These errors are mostly due the other 13 using literature data to supplement our own data. For to the stability of STIS and the accuracy of the flux calibration. an additional 11 galaxies we have data for 2 of the 3 wavelengths We estimate that the contribution from Poisson noise to the error (UV,H,orradio). budget is very small, accounting to less than 1% even in the case of the fainter galaxies observed (NGC 3079 and NGC 4088). For 3. OBSERVATIONS AND REDUCTIONS simplicity, we assume a uniform 5% flux error for all sources. In this section we present the details of our multi-wave-band 3.2. H Observations observations, reductions, and measurements. We also present The H images presented in this paper were obtained in four ultraviolet, optical, infrared, and radio data collected from the lit- observing runs on three different ground-based telescopes: the erature, which are complementary to our observations and will Apache Point Observatory (APO), Kitt Peak National Observa- be used in a forthcoming paper. Table 2 presents the details of the tory (KPNO), and the Cerro Tololo Inter-American Observatory different observations. (CTIO). We also use archival HST narrowband images of NGC 1569 and NGC 4214. These images were complemented with 3.1. Ultra iolet Obser ations v v large-aperture H fluxes from the literature, available for several Ultraviolet images were obtained for 22 of the galaxies in our galaxies that we could not observe. sample (50%), using STIS on board the HST. The observations The APO observations were done with the 3.5 m telescope on of 21 of the galaxies were done as part of the snapshot project the second half of the night of 2000 July 3/4. We used SPIcam, bin- 8721 (PI: D. Calzetti), using the FUV-MAMA detector and the ning 2 pixels in both direction, which gives a scale of 0B28 pixel1 filter F25SRF2. We also obtained HST archival data for IC 1623, and a field of view of 4A8 ; 4A8(1024; 1024 pixels). Two filters which was observed with the same configuration by the project were used for these observations, one centered at 6450 8 with a 8201 (PI: G. R. Meurer). The names of the data sets in the HST bandwidth of 100 8, and one centered at 6590 8 with a bandwidth archive and exposure times of the images are given in Table 2. of 25 8. These filters were used for continuum and line obser- Our images have a pixel size of 0B025 and a field of view of vations, respectively. The continuum observations consisted of 2500 ; 2500 (1024 ; 1024 pixels). The filter used for these ob- two exposures of 300 s for NGC 6217 and two exposure of 90 s servations (F25SRF2) is centered at k1457 8, and has a band- for NGC 6643. The on-band exposure times are given in Table 2. width of 284 8, which is slightly contaminated by geocoronal We also observed spectrophotometric standard stars from Oke O i k1302 8. Guiding problems happened during the observa- (1990). No. 1, 2006 MULTIWAVELENGTH STAR FORMATION INDICATORS 55

TABLE 2 Observations

Ultraviolet H Radio

Exposure Exposure Exposure Name Data Set (s) Observatory (s) Filter Configuration (s) Proposal (1) (2) (3) (4) (5) (6) (7) (8) (9)

ESO 350-38 ...... CTIO 3600 6680/100 BnA 5840 AJ 176 ...... BnA 3750a AJ 176 NGC 232...... CTIO 3600 6680/100 CnB 1670 AS 713 Mrk 555 ...... O63X04WWQ 1320 WIYN-2 720 KP 1494 C 1700 AS 713 IC 1586 ...... C 1650 AS 713 NGC 337...... CTIO 3600 6600/75 C 1680 AS 713 IC 1623 ...... O5CU02010b 3051 ...... CnB 1680 AS 713 NGC 1155...... CnB 1690 AS 713 UGC 2982...... C 1650 AS 713 NGC 1569...... O63X09HYQ 1320 HSTc 1600 F656N B 3910 AA 116 NGC 1614...... C 1710 AS 713 ...... C 1020 AK 331 NGC 1667...... O63X36ITQ 1320 WIYN-2 720 KP 1494 C 1670 AS 713 NGC 1672...... O63X11R0Q 1320 ...... NGC 1741...... O63X38FIQ 1320 WIYN-2 480 KP 1494 C 990 AK 331 ...... B 1770a AM 290 NGC 3079...... O63X35ZXQ 1320 ...... CnB 3050 TT 1 NGC 3690...... C 3740 AS 568 NGC 4088...... O63X12FMQ 1320 WIYN-1 480 W015 C 5380 AL 383 NGC 4100...... C 1680 AS 713 NGC 4214...... O63X39ESQ 1320 HSTd 1600 F656N C 590 AS 713 NGC 4861...... O63X40H7Q 1320 ...... C 1670 AS 713 NGC 5054...... C 1700 AS 713 NGC 5161...... CTIO 3600 6600/75 C 1690 AS 713 NGC 5383...... O63X16UKQ 1320 ...... C 1710 AS 713 Mrk 799 ...... O63X17DRQ 1320 WIYN-1 720 W016 C 560 AS 713 NGC 5669...... O63X18AVQ 1320 ...... C 1700 AS 713 NGC 5676...... O63X19LSQ 1320 ...... C 1680 AS 713 NGC 5713...... O63X20FBQ 1320 ...... C 1690 AS 713 NGC 5860...... O63X21OUQ 1320 WIYN-1 720 KP 1495 C 1690 AS 713 NGC 6090...... WIYN-1 720 KP 1496 CnB 1650 AS 713 NGC 6217...... O63X23BUQ 1320 APO 1200 6590/25 CnB 1660 AS 713 NGC 6643...... O63X24IAQ 1320 APO 1200 6590/25 CnB 1680 AS 713 UGC 11284...... O63X25Y6Q 1320 ...... CnB 1680 AS 713 NGC 6753...... CTIO 4500 6600/75 ...... Tol 1924416...... CTIO 3600 6600/75 CnB 1690 AS 713 NGC 6810...... CTIO 3600 6600/75 ...... ESO 400-43 ...... O63X29FKQ 1320 CTIO 3600 6680/100 CnB 570 AS 713 ...... BnA 3160a AJ 176 NGC 7496...... CTIO 3600 6600/75 CnB 1640 AS 713 NGC 7552...... CTIO 3600 6600/75 CnB 1650 AS 713 ...... A 1590e AS 721 Mrk 323 ...... O63X31GSQ 1320 WIYN-2 960 KP 1494 C 1680 AS 713 NGC 7673...... C 1670 AS 713 NGC 7714...... C 1680 AS 713 Mrk 332 ...... O63X34AHQ 1320 WIYN-2 720 W016 C 1670 AS 713

Notes.—Col. (1): Galaxy name. Cols. (2) and (3): Ultraviolet HST data set name and exposure time. Cols. (4)–(6): Observatory where the H images were obtained ( WIYN-1 and WIYN-2 correspond to the 2001 May and November observing runs), the exposure time of the images, and the name of the filter used for the line observations. Cols. (7)–(9): VLA configuration in which the galaxies were observed, exposure times, and the code of the proposal from which the data were obtained. a These observations were done at 4.89 GHz. b Ultraviolet observations of IC 1623 consist of three exposures (O5CU02010, O5CU02020, and O5CU02030) obtained as part of the HST project 8201 ( PI: G. R. Meurer). c Archival HST data from project 8133 (PI: P. L. Shopbell). d Archival HST data from project 6569 ( PI: J. W. MacKenty). e This observation was done at 1.49 GHz.

The CTIO observations were done with the 1.5 m telescopes H observations are given in Table 2. We also obtained broad on the nights of 2000 August 01/02–08/09. We used the focal R-band images for each of the galaxies, which were used to ratio f/13.5 and the detector Tek 2k No. 6, which gives a scale subtract the continuum contribution from the line images. These of 0B24 pixel1 and a field of view of 8A2 ; 8A2 (2048 ; 2048 broadband images were usually split into three exposures of pixels). The filters and integration times used for the narrowband 500 s each. We observed spectrophotometric standard stars from 56 SCHMITT ET AL. Vol. 164

TABLE 3 Ultraviolet and H Fluxes

8 cor cor ii Name F(1457 ) 3 F(H)int F(H)int F(H)match F(H)match 3 [N ]/H Area Reference (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

ESO 350-38 ...... 33.26 3.33 27.11 2.71 ...... 7.1 0.17 1.5 1 NGC 232...... 4.08 0.41 2.08 0.21 ...... 4.7 0.72 9.2 2 Mrk 555 ...... 1.43 2.8 9.06 0.91 6.66 0.67 3.72 0.37 2.73 0.27 5.1 0.27 ... 3 IC 1586 ...... 2.29 0.22 2.29 0.22 ...... 0.21 143.1 4 NGC 337...... 32.09 3.21 24.32 2.43 ...... 12.0 0.24 16.0 5 IC 1623 ...... 6.58 1.6 ...... 0.30 5.2 6 NGC 1569...... 1.73 7.2 151.85 15.20 151.09 15.10 136.00 13.60 135.30 13.50 50.0 0.04 8.0 7 NGC 1614...... 10.69 1.07 10.69 1.07 ...... 0.44 143.1 4 NGC 1667...... 1.07 1.7 9.18 0.92 5.14 0.51 4.58 0.46 2.47 0.25 9.7 0.69 200.0 8 NGC 1672...... 3.89 2.5 17.70 1.77 17.70 1.77 17.70 1.77 17.70 1.77 ... 0.46 200.0 8 NGC 1741...... 3.95 3.7 12.17 1.22 10.73 1.07 10.20 1.02 9.00 0.90 8.0 0.10 ... 9 NGC 3079...... 0.46 19.3 ...... 1.59 8.0 7 NGC 3690...... 89.13 8.90 89.13 8.90 ...... 0.40 8.0 7, 10 NGC 4088...... 0.67 13.5 62.14 6.21 47.85 4.79 4.36 0.44 3.36 0.34 2.2 0.32 8.0 7 NGC 4214...... 18.36 5.7 83.16 8.32 81.66 8.17 76.80 7.68 75.02 7.50 4.0 0.07 8.0 7 NGC 4861...... 13.07 2.4 19.75 1.98 19.75 1.98 19.75 1.98 19.75 1.98 ... 0.09 143.1 4 NGC 5161...... 9.21 0.92 7.09 0.71 ...... 17.3 0.36 19.6 5 NGC 5383...... 1.08 1.6 43.70 3.60 43.70 3.60 24.20 0.90 24.20 0.90 ... 0.36 8.0 7, 11 Mrk 799 ...... 0.57 7.9 12.80 1.28 8.44 0.84 4.28 0.43 2.82 0.28 4.0 0.50 19.6 2 NGC 5669...... 1.09 13.4 ...... 0.28 8.0 7 NGC 5676...... 0.37 8.9 23.56 2.30 23.56 2.30 ...... 0.45 8.0 7, 12 NGC 5713...... 1.53 28.2 ...... 0.47 16.6 13 NGC 5860...... 1.01 26.9 3.02 0.30 1.83 0.18 3.02 0.30 1.83 0.18 2.1 0.49 143.1 4 NGC 6090...... 8.67 0.87 6.29 0.63 ...... 3.3 0.45 143.1 4 NGC 6217...... 1.86 3.0 20.45 2.05 18.47 1.85 7.99 0.80 7.21 0.72 2.5 0.64 143.1 4 NGC 6643...... 0.80 47.4 29.58 2.96 28.07 2.81 4.37 0.44 4.15 0.42 6.4 0.32 8.0 7 UGC 11284...... 1.07 44.3 ...... 0.38 7.2 2 NGC 6753...... 22.60 2.26 22.60 2.26 ...... Tol 1924416...... 19.05 1.91 18.82 1.88 ...... 6.5 0.02 200.0 8 NGC 6810...... 18.36 1.84 11.86 1.19 ...... 5.9 0.53 8.0 5 ESO 400-43 ...... 3.57 43.0 14.25 1.43 13.35 1.34 14.10 1.41 13.21 1.30 11.2 0.05 ... 14 NGC 7496...... 33.00 3.30 20.72 2.07 ...... 17.5 0.48 200.0 8 NGC 7552...... 71.00 7.10 41.61 4.16 ...... 15.6 0.57 200.0 8 Mrk 323 ...... 0.79 34.3 2.88 0.29 2.88 0.29 2.13 0.21 2.13 0.21 6.6 ...... NGC 7673...... 6.08 0.60 6.08 0.60 ...... 0.23 143.1 4 NGC 7714...... 27.96 2.80 27.96 2.80 ...... 0.36 143.1 4 Mrk 332 ...... 1.37 5.2 13.58 1.36 7.33 0.73 9.22 0.92 4.98 0.50 4.4 0.64 8.0 7

Notes.—Col. (1): Galaxy name. Col. (2): Ultraviolet flux, in units of 1014 ergs cm2 s1 81, not corrected for Galactic extinction; the accuracy of the fluxes is of the order of 5%. Col. (3): 3 detection limit of the UV images in units of 1020 ergs cm2 s1 81 pixel1.Col.(4):IntegratedH flux, not corrected for [N ii] k6548, 6584 8 contamination, in units of 1013 ergs cm2 s1.Col.(5):IntegratedH flux, corrected for [N ii] contamination. Except for NGC 6217 and Mrk 323, galaxies with identical values in cols. (4) and (5) correspond to values obtained from the literature. Col. (6): H flux measured inside an aperture matching that of the UVimage, not corrected for [N ii] k6548, 6584 8 contamination, in units of 1013 ergs cm2 s1. Note that the values for NGC 1672 and NGC 5383 were obtained from the literature and are not contaminated by [Nii]. Col. (7): Same as col. (6), but corrected for [N ii] contamination. Col. (8): 3 detection limit of the H images, in units of 1018 ergs cm2 s1 pixel1.Col.(9):[Nii]/H emission line ratio. Col. (10): Area of the slit used to observe the [N ii]/H ratio. For ESO 400-43, the observations were centered at the nucleus, but the observed area was not given in the paper. NGC 1741 was observed with a slit 1B5 wide, but the length of the extraction was not available. Mrk 555 was observed with a slit narrower than 800, but the size of the extraction was not available. Col. (11): References from which we obtained the emission line ratio [N ii]/H, and for those galaxies for which we did not obtain images, the H flux. References.—(1) Kewley et al. 2000; (2) Veilleux et al. 1995; (3) Terlevich et al. 1991; (4) McQuade et al. 1995; (5) Veron-Cetty & Veron 1986; (6) Corbett et al. 2003; (7) Ho et al. 1997; (8) Storchi-Bergmann et al. 1995; (9) Vacca & Conti 1992; (10) Armus et al. 1990; (11) Sheth et al. 2000; (12) Kennicutt & Kent 1983; (13)Kewleyetal. 2001; (14) Fairall 1988.

Stone & Baldwin (1983) and photometric standards from Landolt tinuum subtraction. The narrowband images were calibrated using (1992) for the calibration of the narrow- and broadband images, observations of spectrophotometric standards from Oke (1990), respectively. while the broadband ones were calibrated using standard stars The KPNO observations were done with the WIYN 3.5 m from Landolt (1992). telescope on two different runs, on the nights of 2001 May 16/17– The data reductions followed standard IRAF procedures, which 18/19, and 2001 November 05/06–06/07 (we refer to these runs started with the overscan and bias subtraction, and the division of as WIYN-1 and WIYN-2, respectively, in Table 2). We used the the images by normalized flat fields. The individual images of Mini-Mosaic, which gives a pixel scale of 0B14 pixel1 and a field each galaxy were aligned, convolved to bring both the line and of view of 9A6 ; 9A6(4096; 4096 pixels). The filters and integra- continuum images to a similar PSF size, and combined to elimi- tion times used for the narrowband H observations are indicated nate cosmic rays. The background was determined from emission- in Table 2. As for the CTIO observations, we obtained two or three free regions around the galaxy, fitted with a polynomial function images of 120 s each in the R band, which were used for the con- to eliminate residual illumination gradients, and subtracted. The No. 1, 2006 MULTIWAVELENGTH STAR FORMATION INDICATORS 57 data were calibrated using the standard star observations, and observed [N ii]/H ratios, the redshifts of the galaxies, and on- the World Coordinate System, obtained from stars in the field of band filter transmission curves used to observe them. Note that the galaxy, was added to the image headers. Whenever needed, the these corrected values are likely to be a lower limit of the real flux, fluxes were also corrected for redshift effects, taking into account since the observed emission-line ratio may still be dominated by where the H line fell on the transmission curve of the filter. the brighter regions of emission. Since these regions are usually The continuum subtraction was done in two different ways. related to the nucleus, which has higher metallicity, they should For the APO observations, the continuum images were not con- also have higher [N ii]/H ratios. taminated by line emission. In this case, these images were scaled Finally, we estimate the errors in our flux measurements. to match the width of the line filter, and then subtracted. We con- A significant part of the error comes from the flux accuracy of firm, by checking stars around the galaxy, that this procedure did the calibration stars, which is of the order of 4%–5%. Other not over or undersubtract the continuum. For all the other observa- effects that can introduce errors of a few percent in the fluxes are tions, we used a similar technique for the continuum subtraction, residuals from the flat-field correction, variations of the sky but had to do it recursively. Since the R-band images, which were transparency overnight, uncertainties in the Galactic foreground used for the continuum, are contaminated by line emission (1.5% reddening correction, and residuals from the sky and continuum of the integrated flux on average), they have to be corrected for subtraction. Poisson noise can also introduce some uncertainties this contribution to their flux; otherwise, a simple subtraction of the in the flux measurements, but this source of error is much smaller scaled R-band image from the line image will underestimate the than 1% in our case. Taking all these sources of error into ac- total H flux. The recursive subtraction was done by first sub- count, we make the conservative assumption that the error in our tracting the scaled continuum image from the line image; then the flux measurements is of the order of 10%. resulting line image was scaled and subtracted from the contin- 3.3. Radio Obser ations uum image, to remove the emission line contribution to this im- v age, and the corrected continuum image was used to subtract the The 8.46 GHz (3.5 cm) radio observations of most of the gal- continuum emission from the original line image. This process was axies in the sample were done with the VLA in two different repeated a few times, until the H and continuum fluxes in regions runs, both part of the project AS 713. The first run was 7 hr long, affected by contamination changed by less than 0.5% between during the CnB configuration, on 2001 June 24. We observed consecutive iterations. This indicated that the process had con- galaxies with <20,or>50, during this run. Most of the verged. We usually needed only 2–3 iterations to reach this level. remaining galaxies were observed on the second run, which was The noise of the final continuum-free images was determined 13.5 hr long during the C configuration, on 2001 July 11. In ad- on emission-free regions of the frame, and the images were dition to these observations, we obtained data from the archive clipped at the 3 level. Total H fluxes [F(H)int] were mea- for those sources that had already been observed with a similar sured by integrating all the emission in these images. For a few of configuration. We also obtained archival 4.89 GHz (6 cm) data the galaxies (e.g., NGC 6753, Tol 1924416) the flux measure- for the galaxies ESO 350-38, NGC 1741, and ESO 400-43, which ment had to take into account foreground stars. In most of the did not have fluxes available in the literature. New 1.49 GHz cases the stars lie in the outskirts of the galaxies, in areas without (20 cm) observations of NGC 7552, not available on the NRAO any H emission. The area around the stars was excluded from VLA Sky Survey (NVSS; Condon et al. 1998), were obtained on the flux measurements, in order to avoid possible subtraction 2002 March 23, during the A configuration, as part of the project residuals that could artificially increase the flux. The only galaxy AS 721. In Table 2 we present the configurations in which the gal- for which a foreground star could present a problem is Tol 1924 axies were observed, the integration times, and proposal codes 416 (Fig. 13). However, even in this case the error caused by the from which they were obtained. star should not account for more than 1% of the integrated flux, All the observations were done in continuum mode with two since the residuals are not very large and the star is in a region of intermediate frequencies (IFs) of 50 MHz bandwidth each, using faint H emission. the radio galaxies 3C 48 and/or 3C 286 as primary calibrators. For those galaxies with H and UV observations, we rotated The phase calibration was done using calibrators from the NRAO and registered the two images, and measured the H flux inside list, preferentially A-category calibrators closer than 10 from the a region matching the one covered by the UV observations galaxies. Most of the observations were done by sandwiching [F(H)match]. These fluxes and detection limits are given in 10 minutes observations of the galaxy with short 2–3 minute Table 3, where we also give integrated H fluxes obtained from observations of a phase calibrator, repeating the process two or the literature, for those galaxies that we did not observe. For three times. The reductions followed standard AIPS techniques, NGC 1672 and NGC 5383, we were also able to obtain pub- which consisted of flagging bad data points, setting the flux- lished H fluxes in regions matching those observed in the UV. density scale using the primary calibrators, and phase calibrating A comparison between F(H)match and F(H)int shows that most using the secondary calibrators. For those sources with peak flux of the H flux originates in the region covered by the UVobser- densities of 1 mJy or higher, we interactively self-calibrate them vations. The median F(H)match/F(H)int value for our galaxies is two or three times in phase. The images were created using uni- 0.92. form weighting. The final resolution of the 8.46 GHz images was Contamination by [N ii] k6548, 6584 is a concern for these of the order of 300, and the maximum angular scales to which the measurements, since it can make a considerable contribution to observations were sensitive is 30. Given that some of the gal- the flux of the images. We deal with this problem by using spec- axies in our sample have diameters of 30 or larger, such as NGC troscopic data from the literature, preferentially large-aperture 6643, our observations may have missed the short spacings, thus spectra. In this way we minimize problems such as enhanced [N ii] resolving out the more extended emission. This is a limitation of emission at the nucleus, which can be due to higher metallicity, or the observations, which can result in fluxes smaller than the real even the presence of a low-luminosity AGN. In Table 3 we give ones, and can be solved by single-dish 8.46 GHz observations. the [N ii]/H ratios, slit areas through which they were observed, Such problems were not an issue at 4.89 and 1.49 GHz, since these ii cor and the H fluxes corrected for [N ] contamination [F(H)int observations were done either with a single dish, or in the most cor and F(H)match]. This correction was calculated based on the compact VLA configuration. 58 SCHMITT ET AL. Vol. 164

TABLE 4 Radio Fluxes

S(1.49 GHz) S(4.89 GHz) S(8.46 GHz)int S(8.46 GHz)match 3 Beam Name (mJy) (mJy) (mJy) (mJy) (Jy) (arcsec) Reference (1) (2) (3) (4) (5) (6) (7) (8)

ESO 350-38 ...... 27.2 0.9 15.1 0.5 10.1 0.2 ... 61 1.37 ; 0.65 1 NGC 232...... 60.6 1.9 56 11 14.9 0.3 ... 70 3.69 ; 2.45 2 Mrk 555 ...... 39.6 1.9 10 45.2 0.2 3.1 0.1 61 4.09 ; 2.96 3 IC 1586 ...... 8.3 0.5 ... 1.7 0.1 ... 83 4.11 ; 2.86 ... NGC 337...... 109.6 4.1 44 11 9.1 0.3 ... 56 5.08 ; 2.99 4 IC 1623 ...... 249.2 9.8 96 12 49.6 0.8 49.0 0.8 93 3.34 ; 2.24 2 NGC 1155...... 9.1 0.6 ... 2.1 0.1 ... 83 3.14 ; 2.19 ... UGC 2982...... 92.4 3.7 28 1 18.2 0.4 ... 62 3.57 ; 2.69 5 NGC 1569...... 338.6 11.0 202 19 23.2 0.5 17.0 0.4 64 1.06 ; 0.84 6 NGC 1614...... 138.2 4.9 63 11 41.1 0.6 ... 71 3.72 ; 2.58 4 NGC 1667...... 77.3 3.0 45 11 17.7 0.4 7.5 0.2 92 4.23 ; 2.78 4 NGC 1672...... 450.0 45.0 114 9 ...... 7 NGC 1741...... 31.7 1.6 6.9 0.6 5.8 0.2 5.0 0.2 105 3.50 ; 2.58 1 NGC 3079...... 770.7 27.1 321 34 120.2 1.9 109.9 1.7 107 1.92 ; 0.99 8 NGC 3690...... 678.1 25.4 300 4 226.0 3.4 ... 79 3.34 ; 2.58 5 NGC 4088...... 174.1 5.9 67 9 22.2 0.5 3.9 0.1 80 3.00 ; 2.71 6 NGC 4100...... 50.3 2.2 ... 26.2 0.5 ... 105 3.99 ; 2.94 ... NGC 4214...... 34.8 1.5 30 7 20.5 0.5 9.7 0.2 112 3.75 ; 3.05 7 NGC 4861...... 14.4 0.9 8.3 0.4 6.3 0.3 6.3 0.3 79 4.19 ; 3.17 9 NGC 5054...... 89.7 3.4 49 11 17.3 0.4 ... 67 5.33 ; 2.63 2 NGC 5161...... 11.3 2.5 ... 1.1 0.2 ... 60 8.38 ; 2.62 ... NGC 5383...... 30.7 1.6 11 55.9 0.2 5.4 0.2 88 4.42 ; 3.02 3 Mrk 799 ...... 67.0 2.7 29 6 14.3 0.4 9.1 0.2 96 4.25 ; 2.76 6 NGC 5669...... 19.0 2.7 ...... 90 4.68 ; 2.95 ... NGC 5676...... 118.8 4.2 38 6 15.4 0.5 4.6 0.2 76 4.16 ; 2.90 6 NGC 5713...... 159.9 5.7 93 14 30.6 0.6 19.2 0.4 81 3.92 ; 2.69 8 NGC 5860...... 7.7 0.5 ... 1.9 0.3 1.9 0.3 115 3.19 ; 2.75 ... NGC 6090...... 48.4 1.5 20.3 1.6 12.9 0.3 ... 75 2.80 ; 1.58 10 NGC 6217...... 80.8 3.1 21 1 13.2 0.2 13.1 0.2 81 3.26 ; 2.13 11 NGC 6643...... 97.8 3.6 34 51.8 0.1 0.4 0.1 75 2.98 ; 2.21 6 UGC 11284...... 60.8 2.5 ... 13.0 0.3 5.5 0.1 70 2.66 ; 2.50 ... NGC 6753...... 35 8 ...... 7 Tol 1924416...... 6.2 0.2 ... 86 4.90 ; 2.56 ... NGC 6810...... 72 8 ...... 7 ESO 400-43 ...... 18.1 1.0 5.3 0.5 4.3 0.2 4.1 0.2 150 5.36 ; 2.03 1 NGC 7496...... 35.0 1.8 ... 7.9 0.2 ... 87 5.48 ; 2.57 ... NGC 7552...... 216.8 8.4 139 11 66.9 1.1 ... 90 5.04 ; 2.58 7 Mrk 323 ...... 25.7 1.4 ... 4.3 0.2 3.3 0.2 80 2.94 ; 2.76 ... NGC 7673...... 32.0 1.9 17 2 10.0 0.2 ... 67 2.99 ; 2.87 12 NGC 7714...... 66.9 2.7 39 9 19.1 0.4 ... 102 4.30 ; 2.87 6 Mrk 332 ...... 37.5 1.7 ... 6.0 0.3 4.0 0.2 105 3.03 ; 2.89 ...

Notes.—Col. (1): Galaxy name. Col. (2): 1.49 GHz (20 cm) fluxes obtained from the NVSS (Condon et al. 1998), except for NGC 7496, which was obtained from Condon (1987), and NGC 7552, which was obtained from our own data. Col. (3): 4.89 GHz (6 cm) fluxes, obtained from the literature, or from new data. Col. (4): Integrated 8.46 GHz (3.5 cm) fluxes, obtained from the data presented in this paper. Col. (5): 8.46 GHz fluxes measured inside an aperture matching the ultraviolet one. Col. (6): 3 detection limit of the 8.46 GHz images. Col. (7): Beam of the 8.46 GHz images. Col. (8): References from which the 4.89 GHz fluxes were obtained. References.—(1) This paper; (2) Griffith et al. 1994; (3) Bicay et al. 1995; (4) Griffith et al. 1995; (5) Condon et al. 1995; (6) Gregory & Condon 1991; (7) Wright et al. 1994; (8) Becker et al. 1991; (9) Klein et al. 1984; (10) van der Hulst et al. 1981; (11) Saikia et al. 1994; (12) Condon & Yin 1990.

The noise of the images was determined in regions free from These values, and the beam sizes of the final images, are presented emission. The total Stokes I fluxes [S(8.46 GHz)int]wereobtained in Table 4. This table also gives large-beam 1.49 and 4.89 GHz by integrating the regions brighter than 3 above the background fluxes obtained from the literature. As for the H emission, we level. The fact that different galaxies can have a range of 2inthe find that most of the 8.46 GHz emission originates in the region 3 sensitivity level does not have a significant impact on their inte- covered by the UVobservations, with a median S(8.46 GHz)match/ grated fluxes, since most of the lower level flux does not cover large S(8.46 GHz)int of 0.7. regions, and the integrated fluxes are dominated by the stronger 3.4. Optical and Infrared Data from the Literature regions. The errors in the flux measurements were calculated by taking into account, in quadrature, a 1.5% uncertainty in the flux Complementary to the images presented in this paper, we also calibration and Poisson noise, which usually dominates the errors. collected infrared, optical, and ultraviolet data from the literature. For the galaxies for which we also have UV images, the radio im- The mid- and far-infrared data, which will be used to determine ages were rotated, registered, and their fluxes were measured inside the infrared luminosities and star formation rates of the galax- a region matching that observed in the UV [S(8.46 GHz)match]. ies, were obtained from IRAS and ISO. These observations are No. 1, 2006 MULTIWAVELENGTH STAR FORMATION INDICATORS 59

TABLE 5 Infrared Fluxes

12 m 25 m 60 m 100 m 150 m 170 m 180 m 205 m Name (Jy) (Jy) (Jy) (Jy) (Jy) (Jy) (Jy) (Jy) Reference (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

ESO 350-38 ...... 0.42 2.49 6.48 5.01 ...... NGC 232...... 0.33 1.08 10.04 18.34 18.9 5.2 15.7 3.9 9.1 1.5 5.4 0.1 1 Mrk 555 ...... 0.28 0.56 4.22 8.68 ...... 5.3 1.6 2 IC 1586 ...... <0.12 <0.21 0.96 1.69 2.1 0.5 ...... 0.8 0.4 3 NGC 337...... 0.22 0.65 8.35 17.11 ...... IC 1623 ...... 0.68 3.57 22.58 30.37 26.7 0.3 23.5 0.4 12.8 0.1 9.7 0.1 1 NGC 1155...... 0.17 0.36 2.45 4.60 ...... UGC 2982...... 0.55 0.78 8.35 16.89 12.5 3.8 9.8 2.9 9.9 3.0 9.2 2.8 2 NGC 1569...... 0.79 7.09 45.41 47.29 ...... NGC 1614...... 1.44 7.29 32.31 32.69 ... 17.1 0.7 ...... 4 NGC 1667...... 0.43 0.68 5.95 14.73 16.3 0.5 17.0 2.8 9.0 0.2 6.3 0.2 1 NGC 1672...... 1.67 4.03 32.96 69.89 ...... NGC 1741...... 0.11 0.58 3.92 5.84 ...... NGC 3079...... 1.52 2.27 44.50 89.22 125.7 18.9 ... 136.9 20.6 134.4 20.3 5 NGC 3690...... 3.81 23.19 103.70 107.40 ...... NGC 4088...... 0.88 1.55 19.88 54.47 ... 144.8 2.5 46.2 9.2 ... 4, 6 NGC 4100...... 0.50 0.82 8.10 21.72 ...... 18.6 3.7 ... 6 NGC 4214...... 0.61 2.36 17.87 29.04 ...... NGC 4861...... <0.13 0.39 1.97 2.46 ...... NGC 5054...... 0.76 1.15 11.60 26.21 ...... 26.7 5.3 ... 6 NGC 5161...... 0.18 0.25 2.18 7.24 ...... NGC 5383...... 0.35 0.69 4.89 13.70 ...... Mrk 799 ...... 0.56 1.63 10.41 19.47 12.9 3.9 ... 11.4 3.4 9.3 2.8 2 NGC 5669...... 0.09 0.12 1.66 5.19 ...... 6.8 1.4 ... 6 NGC 5676...... 0.71 1.03 9.64 30.66 ...... 25.8 5.2 ... 6 NGC 5713...... 1.10 2.58 19.82 36.20 ...... 22.3 4.5 ... 6 NGC 5860...... 0.13 0.20 1.64 3.02 2.6 0.7 ...... 0.7 0.3 3 NGC 6090...... 0.26 1.11 6.66 8.94 8.7 2.2 ...... 4.5 1.1 3 NGC 6217...... 0.51 1.61 10.83 19.33 ... 26.2 0.6 16.1 3.2 ... 4, 6 NGC 6643...... 0.81 1.04 9.38 30.69 ...... 24.7 4.9 ... 6 UGC 11284...... 0.36 1.03 8.25 15.18 27.0 0.2 ... 14.5 0.2 13.5 0.3 1 NGC 6753...... 0.60 0.73 9.43 27.36 ...... 19.0 3.8 ... 6 Tol 1924416...... <0.07 0.42 1.69 1.01 0.7 0.2 ...... 0.1 0.1 3 NGC 6810...... 1.10 3.49 17.79 34.50 29.8 0.1 ... 16.9 0.2 14.0 0.2 1 ESO 400-43 ...... 0.10 0.21 1.59 1.58 ...... NGC 7496...... 0.35 1.60 8.46 15.55 16.2 0.2 13.9 0.5 8.9 0.1 6.3 0.1 1 NGC 7552...... 2.95 12.16 72.03 101.50 ... 104.7 3.6 ...... 4 Mrk 323 ...... 0.27 0.35 3.16 7.91 7.0 2.1 ... 6.5 2.0 6.0 1.8 2 NGC 7673...... 0.13 0.52 4.91 6.89 7.6 1.9 ...... 4.1 1.0 3 NGC 7714...... 0.47 2.85 10.36 11.51 8.0 1.1 ... 5.3 0.8 5.5 0.8 7 Mrk 332 ...... 0.36 0.62 4.87 9.49 6.4 1.9 ... 5.6 1.7 4.7 1.4 2

Notes.—Col. (1): Galaxy name. Cols. (2)–(5): IRAS 12, 25, 60 and 100 m fluxes; we assume that the error of these fluxes is 6%. Cols. (6)–(9): ISO 150, 170, 180 and 205 m fluxes. Col. (9): References from which the ISO fluxes were obtained. Where more than one reference is given, the first is for the 170 mflux,and the second is for 180 m. References.— (1) Spinoglio et al. 2002; (2) Siebenmorgen et al. 1999; (3) Calzetti et al. 2000; (4) Stickel et al. 2000; (5) Perez Garcia et al. 1998; (6) Bendo et al. 2002; (7) Krugel et al. 1998. presented in Table 5. They were obtained with low spatial resolu- surements are given in Table 6. Where we have both STIS 1457 8 tion, of the order of arcminutes, which ensures that only for the and IUE 1482 8 observations, we use the ratio between these two most extended galaxies may we be missing a small amount of emis- measurements to scale the IUE fluxes at longer wavelengths and sion. Nevertheless, even in such cases, the missing flux should be avoid aperture mismatch problems. For the galaxies that only have negligible, since most of the emission is concentrated toward the IUE measurements, we do not try to apply any correction to the nucleus. The estimated uncertainty in the IRAS fluxes is of the or- fluxes. This can result in an uncertainty of a factor of 2 relative to der of 6%, while the errors from the ISO measurements are given the integrated flux (see x 5). We would also like to note that for in Table 5. those galaxies for which only IUE measurements are available, we Ultraviolet, optical, and near-infrared data are presented in do not try to measure matched aperture H fluxes. Table 6. These fluxes, combined with the mid- and far-infrared Optical (U, B, V, and R band) and near-infrared (J, H, and ones, will be used to calculate the bolometric luminosity of the K band) data were obtained from broadband photometry, ex- galaxies. The ultraviolet fluxes were obtained from International trapolated to include the emission from the entire galaxy (de Ultraviolet Explorer (IUE) observations, which have an aperture Vaucouleurs et al. 1991; Jarrett et al. 2003). The errors in the of 1000 ; 2000 (Kinney et al. 1993). The errors in these flux mea- optical and near-infrared flux measurements are 10% and 5%, 60 SCHMITT ET AL.

TABLE 6 Ultraviolet, Optical, and Near-Infrared Fluxes

Name F(1482 8) F(1913 8) F(2373 8) F(2700 8) U B V R J H K Reference (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

ESO 350-38 ...... 8.0 ... 12.4 10.5 11.8 11.5 1 NGC 232...... 7.2 ... 23.9 64.3 78.7 73.4 2 Mrk 555 ...... 27.6 ...... 83.5 104.0 91.5 3 IC 1586 ...... 0.59 0.14 0.48 0.05 ...... 4.7 5.1 7.8 10.8 13.2 10.8 3 NGC 337...... 29.5 63.9 82.6 ... 163.0 180.0 153.0 2 IC 1623 ...... 6.2 ...... 37.2 55.4 54.8 1 NGC 1155...... 2.5 ...... 32.0 35.7 31.0 3 UGC 2982...... 3.3 ...... 56.3 74.0 79.0 2 NGC 1569...... 1.17 0.16 0.81 0.12 0.69 0.13 1.33 0.07 37.1 76.8 141.0 147.0 471.0 549.0 480.0 2 NGC 1614...... 0.56 0.22 0.43 0.08 ...... 6.5 15.1 24.3 23.6 40.3 46.6 53.2 4 NGC 1667...... 0.30 0.18 0.26 0.09 ...... 13.7 33.2 54.1 ... 171.0 218.0 184.0 3 NGC 1672...... 3.01 0.31 2.77 0.18 2.85 0.67 2.90 0.24 139.0 329.0 489.0 473.0 1100.0 1190.0 1040.0 2 NGC 1741...... 14.4 20.4 24.7 ... 12.2 13.9 12.2 3 NGC 3079...... 42.6 103.0 165.0 ... 670.0 903.0 830.0 2 NGC 3690...... 2.33 0.27 1.68 0.15 1.08 0.31 1.02 0.15 ...... 66.2 ... 224.0 296.0 285.0 2 NGC 4088...... 65.7 148.0 217.0 ... 649.0 797.0 680.0 2 NGC 4100...... 29.5 74.7 125.0 ... 413.0 501.0 408.0 2 NGC 4214...... 10.30 0.93 6.34 0.39 4.34 0.34 3.55 0.12 141.0 342.0 446.0 ... 520.0 614.0 458.0 2 NGC 4861...... 9.92 0.98 5.47 0.85 3.34 0.86 2.56 0.67 ... 29.5 43.0 ... 16.8 14.0 13.1 2 NGC 5054...... 32.9 91.5 157.0 203.0 622.0 760.0 614.0 2 NGC 5161...... 26.7 67.5 119.0 134.0 254.0 296.0 235.0 2 NGC 5383...... 25.7 64.5 100.0 ... 249.0 297.0 257.0 2 Mrk 799 ...... 34.8 ...... 157.0 194.0 170.0 3 NGC 5669...... 65.7 ...... 141.0 247.0 169.0 5 NGC 5676...... 30.3 76.1 122.0 ... 410.0 540.0 456.0 3 NGC 5713...... 32.0 78.2 120.0 ... 328.0 369.0 310.0 2 NGC 5860...... 0.74 0.21 0.50 0.11 0.37 0.11 0.46 0.08 ... 8.9 ...... 35.6 42.6 32.5 3 NGC 6090...... 1.07 0.34 0.87 0.11 ...... 10.7 8.6 14.2 16.7 21.4 20.0 6 NGC 6217...... 1.74 0.21 1.55 0.15 ...... 41.1 81.9 125.0 ... 214.0 260.0 226.0 3 NGC 6643...... 38.2 86.6 133.0 ... 297.0 383.0 325.0 7 UGC 11284...... 3.2 ...... 11.7 19.2 19.1 1 NGC 6753...... 26.2 69.4 166.0 231.0 632.0 780.0 724.0 2 Tol 1924—416 ...... 3.81 0.25 2.25 0.33 1.41 0.11 1.19 0.05 12.8 20.4 22.8 11.9 7.1 7.2 5.9 3 NGC 6810...... 15.5 48.0 96.6 161.0 477.0 656.0 565.0 3 ESO 400-43 ...... 8.4 ... 8.2 8.2 10.7 6.1 3 NGC 7496...... 1.43 0.21 1.06 0.08 1.00 0.14 0.87 0.05 ... 72.8 ... 129.0 255.0 298.0 231.0 3 NGC 7552...... 1.72 0.28 1.91 0.19 1.94 0.56 2.32 0.23 52.7 138.0 215.0 285.0 638.0 749.0 645.0 2 Mrk 323 ...... 5.1 12.6 20.6 ... 72.4 87.8 74.3 3 NGC 7673...... 2.29 0.37 1.52 0.11 1.03 0.16 1.00 0.07 13.2 23.0 28.7 ... 39.6 44.5 34.0 3 NGC 7714...... 3.70 0.41 2.55 0.26 1.88 0.27 2.00 0.13 17.3 26.9 37.1 ... 78.1 89.5 83.0 3 Mrk 332 ...... 13.4 27.6 41.0 63.1 115.0 141.0 119.0 3

Notes.—Col. (1): Galaxy name. Cols. (2)–(5): Ultraviolet IUE fluxes from Kinney et al. (1993) in (1014 ergs cm2 s1 81), obtained inside an aperture of 1000 ; 2000, not corrected for Galactic extinction. Cols. (6)–(9): U, B, V,andR fluxes (in mJy) obtained from NED, giving preference to the largest aperture measurements available; the uncertainty of these fluxes is of the order of 10%–15%. Cols. (10)–(12): Near-infrared J, H,andK band fluxes (in mJy); the uncertainty of these fluxes is of the order of 5%. Col. (13): References from which the near-infrared data were obtained. References.— (1) Spinoglio et al. 1995; (2) Jarrett et al. 2003; (3) NED 2MASS; (4) Balzano & Weedman 1981; (5) Bendo et al. 2002; (6) Wu et al. 2002; (7) Aaronson 1977. respectively. These values are ideal for the comparison with FIR from the nucleus (Fig. 1, left). The H and radio images show data. The near-infrared fluxes are mostly from Two Micron All strong emission associated with these regions, besides emission Sky Survey (2MASS) observations, while the optical fluxes were along the spiral arms of the galaxy, which was not covered by the obtained from multiple sources in NED. These broadband fluxes UV image. were converted to monochromatic fluxes using standard filter curves. 4.1.2. NGC 1569 This is a nearby poststarburst galaxy (de Vaucouleurs et al. 4. INDIVIDUAL OBJECTS 1974; Hodge 1974; Israel 1988) strongly affected by Galactic 4.1. Galaxies with UV, H, and Radio Observations foreground extinction (Fig. 1, right). The UV image shows two large clusters, separated by 800 along the NW-SE direction, as well 4.1.1. Mrk 555 as several smaller clusters around them. The H and radio emis- Approximately 30% of the UVemission originates in a circum- sion trace each other, but are anticorrelated relative to the UV. nuclear ring of 100, and we can also see other regions of emission, Regions of strong UV emission have weak H and radio emis- either diffuse or in the form of clumps, at distances larger than 1000 sion, indicating that the gas has been evacuated by winds. Fig. 1.—Radio 8.46 GHz (top panels), H (middle panels), and ultraviolet (bottom panels)imagesofMrk555(left) and NGC 1569 (right). The H and radio images are on the same scale, while the region covered by the ultraviolet image is shown as a box on top of the H contours. The contour levels of the radio images presented in this paper start at the 3 level above the background and increase in powers of 2 (2n ; 3 ), while for the H images they start at the 3 level and increase in powers of 3 (3n ; 3 ). 62 SCHMITT ET AL.

4.1.3. NGC 1667 than the southern one. The radio image, however, only shows The nucleus of this galaxy hosts a low-luminosity Seyfert 2 emission relate to the southern component, in puzzling contra- (Ho et al. 1997). The images (Fig. 2, left) show that the AGN diction to the interpretation of the H image. contributes very little to the overall UV, H, and radio emission. 4.1.9. ESO 400-43 Less than 1% of the UVemission originates from the nucleus of this galaxy (inner 200), where the emission may in part be due to The left column of Figure 5 shows the images of this galaxy. nuclear radiation scattered in our direction, or to circumnuclear The UV image shows a very complicated structure, in which we star formation. Most of the emission in this band comes from can identify several individual clusters, as well as a detached star-forming regions along the spiral arms of the galaxy. The H clump of emission to the north. The H and radio images show image shows significantly stronger emission at the nucleus, re- structures similar to the UV; however, the radio image does not lated to the Seyfert 2 nucleus of this galaxy. It also shows emis- show any emission related to the northern component, probably sion from the star-forming regions along the spiral arms. The due to the sensitivity limit of the observations. radio image shows strong emission related to the galaxy; how- 4.1.10. NGC 6217 ever, because this emission is weak, we were not able to self- calibrate this image, and some closure errors can still be seen. The UV image of this galaxy (Fig. 5, right) shows strong emission related to the nucleus and some fainter emission in the 4.1.4. NGC 1741 outer parts of the image. The H image detects strong nuclear The UVimage shows two clumps of emission, associated with emission, but also detects a large number of fainter star-forming the two nuclei of this galaxy, separated by 400 in the N-S direc- regions along the spiral arms of the galaxy, outside the region cov- tion (Fig. 2, right). These two clumps are surrounded by smaller ered by the UV image. The radio image is not sensitive enough to clusters of emission. We can also see some diffuse emission ex- detect the fainter region of emission seen in H, showing only a tended to the NE of the northernmost nucleus, as well as a tidal nuclear source and two faint point sources in the field, one of tail extending to the E. The H emission has a distribution sim- which is not related to the galaxy. 0 ilar to the UV, and also shows two tidal tails extending for 1 to 4.1.11. NGC 6643 the SE and SW. The radio image shows emission associated only with the double nucleus, where we can see that the stronger radio The left panel of Figure 6 presents the UV image of this gal- source corresponds to the fainter UV nucleus. The UV image was axy, which is mostly empty, showing only two faint point sources. registered to the H image, which is consistent with the radio. The H image shows regions of star formation throughout the galaxy disk, while the radio image shows only two point sources. 4.1.5. NGC 4088 Most of the diffuse emission seen in H is not detected in the radio The UV image is mostly empty, presenting only one strong due to the sensitivity limit of the observations. clump of emission and some diffuse emission (Fig. 3, left). The H 4.1.12. Mrk 323 image shows emission related to star-forming regions throughout the disk of the galaxy. The radio image shows emission related to The UV image of this galaxy shows only two point sources in stronger star-forming regions of the galaxy, but is not deep enough the northern border of the image (Fig. 6, right), which correspond to detect the fainter, more diffuse regions seen in H. to a region of strong H emission. The H image also shows some fainter emission around the nucleus of the galaxy, which is 4.1.6. NGC 4214 related to the strongest region of radio emission. The UV image shows one strong clump of emission at the 4.1.13. Mrk 332 nucleus and another clump on the eastern border of the image (Fig. 3, right). As for NGC 1569, the H and radio emission The UV image of this (Fig. 7) presents strong trace each other, but are very faint in regions of strong UVemis- emission associated with the nucleus, as well as several star- sion, indicating that the gas has been evacuated from these re- forming regions along the spiral arms. The H emission traces gions. Note that this galaxy is close enough to allow us to resolve what is seen in the UV, and also shows strong emission along the individual stars in the STIS image. spiral arms, outside the region covered by the UV image. The radio shows only a strong nuclear point source, and some faint 4.1.7. Mrk 799 emission corresponding to the spiral arms. The UV image of this galaxy (Fig. 4, left) shows some faint 4.2. Galaxies with UV and Radio Observations emission, either diffuse or in the form of clumps, related to the spiral arms of the galaxy. The H and radio images trace this 4.2.1. IC 1623 emission at the nucleus and, besides the region of strong emis- This is an with a double nucleus (Knop sion 2000 to the SE and some faint emission to the N of the nu- et al. 1994). The UV image (Fig. 8, top) shows only the western cleus, outside the region covered by the UV image. component, while the eastern one is completely enshrouded by dust, being visible only at longer wavelengths. The radio image 4.1.8. NGC 5860 shows emission related to both components; however, the stronger The images of this are presented in the right source is related to the eastern, more obscured, structure. A de- column of Figure 4. Note that all the panels are shown on the tailed study of the UV image of this galaxy is presented by same scale, so we do not show the box indicating the region cov- Goldader et al. (2002), who found that both components have ered by the UVobservations in the H image. The UVemission similar bolometric luminosities. is distributed in two regions of similar intensity, separated by 1200 along the N-S direction. The H image shows strong emission 4.2.2. NGC 3079 associated with the southern component, but only fainter emis- This is an edge-on spiral galaxy, with several regions of star sion related to the northern one, suggesting that it may be older formation along the disk (Cecil et al. 2001). The UVimage (Fig. 8, Fig. 2.—As in Fig. 1, but for NGC 1667 (left) and NGC 1741 (right). Fig. 3.—As in Fig. 1, but for NGC 4088 (left)andNGC4214(right).

64 Fig. 4.—AsinFig.1,butforMrk799(left) and NGC 5860 (right). All NGC 5860 images are presented on the same scale, so we do not show the region covered by the UV emission in the H image.

65 Fig. 5.—As in Fig. 1, but for ESO 400-43 (left)andNGC6217(right).

66 Fig. 6.—As in Fig. 1, for NGC 6643 (left)andMrk323(right).

67 68 SCHMITT ET AL.

middle) is mostly empty, showing only traces of emission, due to the high amount of extinction along the line of sight. The radio image shows a strong point source at the nucleus and a lobe at 2000 NE, both related to a hidden AGN (Duric et al. 1983). The radio image also shows strong emission along P.A.¼15, re- lated to star forming regions along the galaxy disk. The H im- age from Cecil et al. (2001) shows strong emission along the disk, as well as a nuclear outflow, related to the radio lobe. 4.2.3. NGC 4861 The bottom panels of Figure 8 show the UV image of this nearby starburst galaxy. The emission is divided into two large clumps, one corresponding to the nucleus, in the center of the image, which is composed of several smaller clusters. The sec- ond clump is more diffuse, located 900 to the NE. The radio image shows strong emission related to the nucleus, but nothing toward the NE structure. Dottori et al. (1994) presented an H image of this galaxy, which shows emission related to all the structures seen in the UV. 4.2.4. NGC 5383 The UV image of this galaxy (Fig. 9, top left) shows several clusters, as well as some diffuse emission, extended for 2000 in the E-W direction in the form of a ring, or inner spiral arms. Comparing this image with the H image presented by Sheth et al. (2000), we see that they trace each other, with the regions of strong H emission following the regions with strong UV. The overall structure of the radio emission (Fig. 9, top right) is sim- ilar to the H and UV. However, when they are compared in de- tail we find that the peak of the radio emission is located in a region with little or no UV and H emission. This enhanced ra- dio emission could be related to a region of star formation hidden by dust, or to the nucleus of the galaxy. The latter possibility implies that this galaxy harbors a low-luminosity AGN. If this is true, this AGN should be completely hidden, since Ho et al. (1997) classified this galaxy as H ii. 4.2.5. NGC 5676 The middle panels of Figure 9 presents the UV and radio im- ages of this galaxy. Only faint emission is detected in the UV. The radio image also shows faint emission in the same region covered by the UV observations, indicating that the faint emis- sion is due to a low star formation rate rather than obscuration. A region with stronger radio emission is seen to the north of the nucleus, and outside the STIS field of view. 4.2.6. NGC 5713 The UV and radio images of this galaxy are presented in the bottom panels of Figure 9. The UVemission shows several asso- ciations, with the strongest ones located to the northern part of the image. The radio emission is concentrated in a string of knots, aligned with the structures seen in the northern part of the UV im- age. The two easternmost knots correspond to regions of emission in the UV,but the third one, around right ascension 14h40m10.s7, is related to a region without UV emission. Conversely, analyzing the regions to the west of the UV image, we can detect strong UV emission, but only weak radio emission is associated with these structures. 4.2.7. UGC 11284 This is an interacting galaxy in which the eastern component presents stronger H emission than the western one (Bushouse Fig. 7.—As in Fig. 1, but for Mrk 332. 1986). The UVobservations were centered on the eastern compo- nent, but we detect only a faint compact source coincident with the Fig. 8.—Ultraviolet (left) and radio 8.46 GHz (right)imagesofIC1623(top), NGC 3079 (middle), and NGC 4861 (bottom). For IC 1623, both images are shown on the same scale, while for NGC 3079 and NGC 4861 the region covered by the ultraviolet image is shows as a box superimposed on the contours. Fig. 9.—As in Fig. 8, but for NGC 5383 (top), NGC 5676 (middle), and NGC 5713 (bottom). The region covered by the ultraviolet image is shown as a box superimposed on the contours. MULTIWAVELENGTH STAR FORMATION INDICATORS 71

Fig. 10.—As in Fig. 8, but for UGC 11284. radio peak and some diffuse emission to the east, which is also vis- lated to the nucleus (Fig. 12, top). The radio image shows emis- ible in the radio (Fig. 10). The radio image shows the two galaxies sion at the nucleus, and some faint emission related to the host and some faint emission between them. As in H, the eastern com- galaxy. ponent is the strongest, suggesting that the star-forming region is highly reddened, or the possible presence of a hidden AGN. The 4.3.5. NGC 6090 integrated 8.46 GHz flux given in Table 4 corresponds to the flux The middle panels of Figure 12 present the H and radio im- of the two galaxies, to be consistent with the region covered by the ages of this galaxy, which have similar structures. The emission FIR observations. is divided into two major knots, separated by 600 along the NE- SW direction. The NE structure can be divided into two compo- 4.3. Galaxies with H and Radio Observations nents separated by 200 in the N-S direction. 4.3.1. ESO 350-38 4.3.6. NGC 7496 The H and radio emission of this starburst galaxy (Fig. 11, top) show a good agreement. Both images show a Y-shaped struc- This galaxy has a low-luminosity AGN in the nucleus, classi- ture at the nucleus, with the strongest emission coming from the fied as a Seyfert 2 (Kinney et al. 1993); nevertheless, it also shows center. The H image shows some diffuse emission surrounding strong circumnuclear star formation. The bottom panels of Fig- this Y-shaped structure, which is not seen in the radio. The UVim- ure 12 present the H, which shows several blobs of emission 00 age of this galaxy (Kunth et al. 2003) shows strong emission re- around the nucleus, a strong region of emission at 40 NW, and lated to the east and south components, but only faint emission some faint star-forming regions along the disk. The radio image related to the strong nuclear source seen in H and radio. shows emission related to the nuclear and circumnuclear region and a faint point source at 10 N. 4.3.2. NGC 232 4.3.7. NGC 7552 The middle panels of Figure 11 present the H and radio im- ages of this galaxy, which shows strong H emission concen- This is a nuclear starburst galaxy. The H and radio images trated at the nucleus and in a blob at 3B5 Wof it. We also see more (Fig. 13, top) show the presence of a circumnuclear ring, as well diffuse emission extended along P.A. 40, which is in the di- as star formation along the bar of the galaxy (similar structures rection along which the radio emission is extended. were detected by Hameed & Devereux 1999). The H image also shows some emission along the spiral arms, which is too 4.3.3. NGC 337 faint to be detected by our radio observations. This galaxy presents diffuse H emission distributed through- out the disk (Fig. 11, bottom), as well as some clumps with 4.3.8. Tol 1924416 stronger emission. The structure of the radio emission is similar The bottom panels of Figure 13 show the H and radio images to that seen in H; however, a significant part of the diffuse emis- of this galaxy. The emission in these bands is very similar, two sion is resolved out in the radio image, because the observations blobs separated by 600 along the E-W direction. The H image do not have short spacings. shows some diffuse emission surrounding these structures, which is not seen in the radio. A detailed high spatial resolution study of 4.3.4. NGC 5161 this galaxy was presented by O¨ stlin et al. (1998), who detected a The H image of this galaxy presents small star-forming re- large number of star clusters in this galaxy. These starbursts show gions along the spiral arms, as well as some faint emission re- peaks in the age distribution, with the younger ones being found in Fig. 11.—H (left) and radio 8.46 GHz (right) images of ESO 350-38 (top), NGC 232 (middle), and NGC 337 (bottom). The H and radio image are on the same scale.

72 Fig. 12.—As in Fig. 11, but for NGC 5161 (top), NGC 6090 (middle), and NGC 7496 (bottom).

73 74 SCHMITT ET AL.

Fig. 13.—As in Fig. 11, but for NGC 7552 (top)andTol1924416 (bottom). the starburst region. The galaxy is in a merging state, which prob- 4.4.3. UGC 2982 ably caused the starburst. At 1000 SW from the westernmost H The radio emission of this galaxy is presented in the middle blob we see some image defects due to residuals from the con- left panel of Figure 14. It is diffuse and extended for approxi- tinuum subtraction of a foreground star. mately 4500 along the E-W direction. 4.4. Galaxies with Observations in a Single Band 4.4.4. NGC 1614 4.4.1. IC 1586 The 3.6 cm image of this galaxy consists of a strong point This galaxy was observed only in the radio. The 3.6 cm image source, surrounded by faint emission, extended by 2500 in the (Fig. 14, top left), shows two faint blobs, separated by 700 in the E-W direction (Fig. 14, middle right). The structure of the radio NE-SW direction. emission is similar to that seen in H (Armus et al. 1990). 4.4.2. NGC 1155 4.4.5. NGC 3690 The radio emission of this galaxy presents only a compact The bottom left panel of Figure 14 presents the radio image of source (Fig. 14, top right). this galaxy. The bulk of the emission is concentrated in a region Fig. 14.—Radio 8.46 GHz images of IC 1586 (top left), NGC 1155 (top right), UGC 2982 (middle left), NGC 1614 (middle right), NGC 3690 (bottom left), and NGC 4100 (bottom right). 76 SCHMITT ET AL. Vol. 164 with a diameter of 5000. The emission in this region consists of several blobs and some faint emission surrounding it. Fainter emission can be seen toward the NW. The radio and H emission of this galaxy have similar structures (Armus et al. 1990). 4.4.6. NGC 4100 Most of the radio emission of this galaxy (Fig. 14, bottom right) is very faint and diffuse, close to the detection limit of the obser- vation. A region with stronger emission is seen around the nucleus. 4.4.7. NGC 5054 The radio image of this galaxy, presented in the top panel of Figure 15, shows stronger emission at the nucleus, surround by a region of fainter and diffuse emission, with a radius of 4000. 4.4.8. NGC 7673 The middle panel of Figure 15 shows the radio emission of this galaxy, which has the form of a ring, composed of three knots, more or less centered around the nucleus. Homeier & Gallagher (1999) presented the H imageofthisgalaxy,whichhasastruc- ture similar to the one seen in the radio. Their image also shows a region of strong emission between the two brighter radio struc- tures, which does not seem to have a counterpart in the radio. 4.4.9. NGC 7714 The radio emission of this galaxy presents a strong point source at the nucleus (Fig. 15, bottom) and some diffuse emis- sion around it, extending by approximately 3000 in the NW-SE direction. This structure is similar to the one seen in H by Gonza´lez Delgado et al. (1995). 4.4.10. NGC 1672 The UV image of this galaxy is presented in the left panel of Figure 16. It shows a structure resembling a half ring, with sev- eral clusters of stars along it. The regions of stronger UV emis- sion are coincident with those of strong H emission seen by Storchi-Bergmann et al. (1996). 4.4.11. NGC 5669 The UV image of this galaxy (Fig. 16, right) shows enhanced emission along the bar (NE-SW), as well as some emission along the inner spiral arms, which are seen in the form of a ring, close to the borders of the image. We obtained VLA 8.46 GHz data for this galaxy, but could not detect any radio emission. Lower resolution (4500 beam), lower frequency (1.4 GHz) ob- servations from the NVSS catalog (Condon et al. 1998), de- tected this source. Nevertheless, higher resolution observations (4B5 beam) at the same frequency, from the FIRST catalog (Becker et al. 1995), did not detect it either. This suggests that the star formation in this galaxy is faint and widespread, re- sulting in radio emission below the detection threshold of our 8.46 GHz observations. 4.4.12. NGC 6753 The left panel of Figure 17 presents the H image of this galaxy, which is distributed throughout the disk and spiral arms. The latter can be seen as a ring structure extended along the NE-SW direction. Note that the two bright sources to the south of the galaxy are residuals due to foreground stars, left over from the subtraction of the continuum. 4.4.13. NGC 6810

The H image of this galaxy (Fig. 17, right) shows strong Fig. 15.—As in Fig. 14, but for NGC 5054 (top), NGC 7673 (middle), and emission, extended for 10 along the N-S direction, in a rectangular NGC 7714 (bottom). No. 1, 2006 MULTIWAVELENGTH STAR FORMATION INDICATORS 77

Fig. 16.—Ultraviolet images of NGC 1672 (left) and NGC 5669 (right). region. This emission is composed of several individual knots. for 22 of these galaxies, H images for 23 galaxies, and radio Diffuse emission, extending over a region of 8000 in diameter, is 8.46 GHz images for 39 galaxies. We also obtained H data from seen along the SE-NW direction, possibly related to outflows. An- the literature for another 14 galaxies which we could not ob- other interesting structure that can be seen in this image is a half- serve, as well as complementary multifrequency radio, infrared, ring of small knots, to the east of the rectangular region described and optical data for all the galaxies in the sample. above. This ring extends along the major axis of the galaxy, has a A preliminary comparison between the UV, H, and radio im- diameter of 10000 in the N-S direction, and lies along the border ages presented in this paper shows that, overall, on a larger scale, of a dust lane. Observations by Hameed & Devereux (1999) found there is a good agreement in the spatial distribution of the differ- similar structures. ent star formation indicators. Regions of intense star formation usually show up as strong regions of emission at all wavelengths. 5. DISCUSSION AND SUMMARY The relation between the different star formation indicators will In this paper we present the compilation of a database of mul- be explored in more detail in an accompanying paper, but the tiwavelength data for a sample of 41 nearby star-forming gal- current results already suggest that these three indicators trace axies. We present observations and reductions of UV images each other, at least within the physical parameter space covered

Fig. 17.—H images of NGC 6753 (left)andNGC6810(right). 78 SCHMITT ET AL. Vol. 164

Fig. 18.—Left: Spectral energy distributions of the 29 galaxies for which we have at least one ISO band. Galaxies with SEDs dominated by the FIR emission are presented in red (REDSED), while those with comparable optical and FIR fluxes are presented in blue (BLUESED). The thick dashed lines indicate the average SED of each group ( Table 7). Right: BLUESED and REDSED (solid blue and red lines, respectively) are compared to the low (SBL) and high (SBH) reddening SEDs from Schmitt et al. (1997; blue and red dashed lines, respectively). In both panels we show the wavelength scale in the top axis and indicate the different wave band regions inside the panels. by our sample. However, an important effect that should be taken SEDs of 29 of our sample galaxies are plotted with normalization into account when dealing with shorter wavelength measurements of unity at 1.49 GHz (20 cm). For galaxies for which 1.49 GHz (UV and H) is dust obscuration, which can easily absorb, or was not available, we extrapolated the flux from higher frequen- 1 even hide, entire regions of a galaxy. The most noticeable ex- cies, assuming S / . The 29 galaxies are those for which ample of such effect is IC 1623, for which the eastern component at least one ISO FIR data point beyond 100 m is available. In can be detected only in the radio, while the western one can be the case of NGC 4088 we exclude the measurement at 170 m, seen at both UV and radio. Similar results can also be seen in which has calibration problems, and use only the one at 180 m other galaxies. (Table 5). All data are integrated fluxes, except for the UV points, Despite the good agreement between the different wave bands which were measured with a smaller field of view. We did not try described above, a detailed inspection of individual sources shows to apply corrections to the UV data for aperture mismatch. In most that in some cases there are deviations from this pattern, which cases, the mismatch between the UV values and the integrated val- cannot be attributed to dust. One such example is NGC 6643, for ues at longer wavelengths is at the level of a factor of 2 or less. which the UV image is almost empty, while the H one shows This factor is inferred from a comparison of the H and 8.46 GHz several regions of emission throughout the disk of the galaxy, and fluxesmeasuredinsideanaperturematchingtheUVone,andtheir the radio shows only two small regions of emission. The differ- corresponding integrated values (xx 3.2 and 3.3). Thus, the SEDs ences from the expected picture can be attributed in part to the fact plotted in Figure 18 can be considered representative of each gal- that the star formation in this galaxy is mostly faint and diffuse, so axy’s SED even in the UV. the UV emission could have easily been absorbed by dust. In the This collection of normalized SEDs of normal star-forming case of the radio 8.46 GHz emission, the observations were not galaxies readily shows a number of characteristics. (1) The range sensitive enough to detect the faint diffuse emission along the disk in FIR luminosity is fairly modest, once the SEDs are normalized of the galaxy, but this emission was clearly detected by the large- to the radio, a factor of 5–6, clearly a reflection of the tight FIR- beam observations at lower frequencies. Two other galaxies that radio correlation found for galaxy populations (de Jong et al. present interesting behavior are NGC 1569 and NGC 4214. Based 1985; Helou et al. 1985). (2) The range in FIR luminosity is much on a visual inspection of their UVimages, we can clearly see bright smaller than the factor of 200 spanned by the UV and 100 star clusters, which indicates that they are not strongly absorbed. spanned by the optical; the large UVand optical variation is likely Nevertheless, when these images are compared to the H and a combination of variations in the stellar population content and radio ones, we find that the emission in these wave bands is dis- the dust obscuration, with the latter contributing to the larger placed relative to the clusters, suggesting that the region around spread observed in the UV. (3) Relatively ‘‘blue’’ SEDs at optical them was evacuated by winds. Although not all galaxies show wavelengths [those for which F()opt F()FIR] do not neces- these effects, they can have a significant impact on the determi- sarily correspond to blue galaxies in the UV as well; this likely nation of star formation rates. reflects the stellar population content of the galaxy, where the The broad wavelength range spanned by our data is better ap- ‘‘optically bright’’ populations are likely evolved stars, no longer preciated in the left panel of Figure 18, where the UV-to-radio UV-bright and contributing to the star formation. No. 1, 2006 MULTIWAVELENGTH STAR FORMATION INDICATORS 79

TABLE 7 Schmitt et al. (1997). We can see that there is a good agreement Spectral Energy Distributions between the two red SEDs, SBH and REDSED, over the entire frequency range. However, in the case of the blue SEDs, SBL and log F BLUESED, the agreement is good only in the radio–FIR range, Band log (Hz) REDSED BLUESED with the BLUESED presenting higher fluxes in the optical-NIR range, but smaller flux in the UV. These differences can be attrib- 1457 8 ...... 15.31 3.83 4.26 uted to aperture effects. The SEDs created with the current data- B ...... 14.83 4.89 5.58 base include the entire galaxy, with the exception of the UV flux. J...... 14.38 4.94 5.78 In the case of the Schmitt et al. (1997) SEDs the UV, optical, and H...... 14.26 4.92 5.76 NIR measurements were obtained with apertures similar to that of K...... 14.14 4.77 5.56 00 ; 00 12 m...... 13.40 4.95 5.13 IUE (10 20 ), while the radio and infrared measurements 25 m...... 13.08 5.15 5.11 included the entire galaxy. This aperture difference is not a signifi- 60 m...... 12.70 5.61 5.65 cant problem for the infrared-dominated SEDs, since they are 100 m...... 12.48 5.53 5.78 usually dominated by a reddened nuclear starburst. Nevertheless, 150 m...... 12.30 5.34 5.51 in the case of larger galaxies, without a nuclear starburst, older 170 m...... 12.25 5.21 5.42 stars make a significant contribution to the integrated light of the 180 m...... 12.22 5.06 5.39 galaxy, resulting in the similar optical-to-FIR peak ratio observed in 205 m...... 12.16 4.87 5.09 the BLUESED, and in larger optical-to-UV ratios than observed in 8.46 GHz...... 9.93 0.13 0.06 the low-reddening starburst SED of Schmitt et al. (1997). 4.89 GHz...... 9.69 0.17 0.09 1.49 GHz...... 9.15 0.00 0.00

Notes.—First two columns give the band and the corresponding logarithm of the frequency, respectively; next two columns give the average SEDs of gal- This work was partially supported by the NASA grants HST- axies dominated by the FIR emission (REDSED) and those with similar con- GO-8721 and NAG5-8426. The National Radio Astronomy tributions from the optical and the FIR part of the spectrum ( BLUESED). These Observatory is a facility of the National Science Foundation, op- SED are normalized to the energy density at 1.49 GHz. erated under cooperative agreement by Associated Universities, Inc. This research made use of the NASA/IPAC Extragalactic The thicker dashed lines in the left panel of Figure 18 identify Database (NED), which is operated by the Jet Propulsion Lab- the two basic templates that can be recognized in our modest col- oratory, Caltech, under contract with NASA. We also used the lection of SEDs (the average values are given in Table 7): (1) the Digitized Sky Survey, which was produced at the Space Tele- FIR-dominated SED (REDSED), created by averaging 11 galax- scope Science Institute under US government grant NAGW- ies, where the observed UV-optical emission is heavily affected by 2166. H. R. S. would like to acknowledge the NRAO Jansky dust and provides only a modest contribution to the galaxy energy Fellowship program for support during most of the stages of budget; and (2) the optical–FIR SED (BLUESED), created by av- this project. H. R. S. would also like to thank the Spitzer Science eraging 18 galaxies, where the evolved stellar populations are as Center and the Space Telescope Science Institute visitor programs important as the star-forming (FIR-emitting) population for the for their support. UVobservations were obtained with the NASA/ galaxy’s energy budget. Due to their large wavelength range, these ESA Hubble Space Telescope at the Space Telescope Science In- two basic templates can be used to gain insights in the properties stitute, which is operated by the Association of Universities for of intermediate and large redshift galaxies. Research in Astronomy, Inc., under NASA contract NAS5-26555. We also present, in the right panel of Figure 18, a comparison Basic research at the US Naval Research Laboratory is supported between the SEDs created in this paper and those of high- and by the Office of Naval Research. We would like to thank the ref- low-reddening starbursts (SBH and SBL, respectively) from eree for comments that helped us improve this paper.

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